This invention is concerned with a device which stores, as tone source data, data obtained through analyzation of original tone waveform data for each data segments thereof for subsequent tone synthesis and which thus is suitable for use as a tone source device in electronic musical instruments or the like.
To this day, there have been proposed various tone signal forming techniques that are suitable for use in electronic musical instruments. Most typical of such techniques are FM (Frequency Modulation) type tone source and waveform memory type tone source techniques. The FM type tone source technique synthesizes (frequency-modulates) a plurality of basic or original signals at various magnitude in accordance with various algorithms (U.S. Pat. No. 4,018,121, for example). The waveform memory type tone source technique, on the other hand, stores tones of a natural musical instrument etc. in time series in advance, and, when actually generating reproduced tones, it sequentially reads out the stored tones to form tone waveform data (U.S. Pat. No. 4,383,462, for example). In addition to the above-mentioned techniques, Fourier synthesis type tone source technique is well-known in the art (U.S. Pat. No. 3,809,786). Another synthesis type tone source techniques is also known from U.S. Pat. No. 5,029,509.
With the FM type tone source, waveform can be controlled in various manners with substantial flexibility by adjusting parameters, but it is difficult to control waveform so as to achieve a desired tone color, and hence satisfactory reproduction of natural musical instrument tones can hardly be achieved. With the waveform memory type tone source, satisfactory reproduction of natural musical instrument tones can be achieved, but it is difficult to process waveform, and hence tone color can not be varied as desired. Further, both the FM type and waveform memory type tone sources can not realize an intermediate tone color from those of plural tone data to a satisfactory degree. That is to say, the FM type tone source has inherent adverse characteristics that an intermediate value of plural parameters never corresponds to an intermediate value of plural tone colors, and the waveform type tone source can never generate significant data even if it obtains an intermediate data value at each sampling time.
In addition, with the Fourier synthesis tone source respective Fourier components of a tone to be synthesized are undesirably fixed in their frequency relations with respect to each other, and it is not possible to vary the frequencies of the individual components as desired. Further, the Fourier synthesis tone source is basically not arranged in such a manner that arbitrary or desired tone waveform data provided from outside are freely sampled for subsequent analyzation and then tone data of desired characteristics are freely formed on the basis of the analyzed data.
Moreover, in general, the waveform type tone source requires looped readout of the waveform memory because its memory capacity for storing the waveform data is limited. So, this tone source suffers from the disadvantage that connect ion points of the looped readout will result in unnaturalness of generated tones.
In the meantime, in the case of wind instruments such as a saxophone, rise time and duration of the attack portion of a generated tone will substantially vary depending on whether the instrument is played strongly or weakly. So, in order to approximate such variations using the waveform memory type tone source, it is necessary to expand or contract the data readout time length. However, the prior art waveform memory type tone source is not satisfactory in that it can not effectively change the attack speed etc. in response to the intensity of a performance action, because a change in the readout speed will entail an undesirable change in the tonal frequency.
Further, in the case where vibrato, which is a well-known method for tonal decoration, is to be effected by the FM type tone source, there will arise the inevitable problem that the performance tends to become extremely monotonous because the FM modulation is made by the use of regularly formed triangle wave, sine wave or the like. In addition, if vibrato effect is previously provided to the waveform data itself, the source can not achieve vibrato control, nor can it provide good matching of the vibrato waveform in the event that repeated readout of the waveform data is started halfway rather than the very beginning.